Here at Tapflo we have a large range of Diaphragm Pumps to handle any application so we know how overwhelming it can be to figure out which you need. Our whole range is air operated (AOD), so all you need for your Tapflo pump to work is a line of compressed air. It's as easy as that - plug and go. We're here to run you through some of the questions you may be having about your options when choosing your next Air Pump, so sit back as we try to make the process as easy as possible for you.  

An image of a diaphragm pump and an article about choosing the right diaphragm pumps

Why Choose a Diaphragm Pump?

An Air Operated Diaphragm Pump is the best solution for any application where you are required to move high volumes at a low pressure. 

Diaphragm Pumps have become a popular choice of pump for many businesses for a few very important reasons, one of which is the reduced risk of air contamination.An Air Pump is powered by exactly that, air, some Diaphragm Pumps are also electrically driven, this means that oil isn't necessary within your pump which could potentially be harmful to your pumping process by contaminating the pump's surrounding environment of even your product! 

Diaphragm Pumps are a type of positive-displacement pump. Pressure is used to operate the valves or flappers, opening and closing them to provide a pumping action. 

AOD Pumps are robust due to the diaphragms within your pump being made from PTFE rathe thana  piston and cylinder system which will cause wear to the internals of your pump. 

How Does a Diaphragm Pump Work?

We talk a lot about the benefits of using a Diaphragm Pump and how easy they are for anyone to use, even without technical training, so let's take a quick look at the way these pumps operate:

1. Downstroke

The first stage of the operating principle of an Air Pump is the down stroke action, the PTFE diaphragm gets pulled down, and the volume inside the head of the pump increases. The volume expansion causes the pressure inside the pump head to drop below the pressure of the inlet and exhaust.

The higher pressure of the inlet makes the inlet valve open up, whilst the higher pressure of the exhaust keeps the outlet valve shut.

The product is pushed from the inlet into the pump head, through the valve.

2. Upstroke

During the upstroke motion, the diaphragm gets pushed upward, so the volume in the pump head decreases.

The pressure of the pump head then becomes higher than the pressure at the inlet and exhaust. This pressure keeps the inlet valve shut while allowing the exhaust valve to open which expels the product you are pumping out of the pump's exhaust valve.

This should give you a basic understanding of how the pump operates in order to move product from the inlet valve through the pump. Due to the positive nature of an AOD Pump, they are extremely versatile. To ensure you choose the right Diaphragm Pump for the job, we're going to run you through some of the tehcnica details that need to be taken into account.

Volume needs of an AOD

The first factor you should consider is the volume of material you'll need to move.

Air Pumps come in an array of sizes so it's likely that we've got something to fit your needs. There are Diaphragm Pumps that can move about a gallon of material per minute - and then there are pumps that can move hundreds of gallons in a minute. It all depends on the size of the pump and how fast it works.

It is important to note that your required volume will affect the speed at which the pump can operate. The amount of space in the pump head affects how fast material can be pumped through, so you'll need to get a bigger pump if you want it to move more material, or to move material faster.

You'll want to choose a pump that runs at about half of its maximum capacity during ordinary use. This way, the pump will last a long time with minimal wear to the pump's internals, therefore requiring less maintenance. If your pump is always running at close to 100 percent capacity, you'll need to buy a replacement sooner.

You can easily find out the capacity of a pump before you buy - just check the product pages for more information or ask a member of the Sales Team.

To find out more about maintaining your Diaphragm Pump, head over to our 'How To' guide

Drive Type

You should also think about the type of drive behind the diaphragm. As we mentioned before, there are 2 types of drive options available with Diaphragm Pumps, electrically driven and air operated Diaphragm Pumps 

The drive can affect where you can use the pump and how safely you can operate it. For example, if you choose electrically driven pumps, they'll work anywhere electricity is available. However, in areas where a flammable material is nearby, they aren't a safe choice. This is a pro of using an Air Operated Diaphragm Pump, particulalry as Tapflo can supply our AOD Pumps as ATEX rated. 

An air-driven pump can be used anywhere, as long as compressed air is available. You can use air-driven pumps around flammable and toxic materials without concern, because the air can't ignite anything.


One of the obvious differences in our Diaphragm Pump range is the material your pump can be manufactured from. We have a few options such as Metal, PTFE or HDPE.

There are usually a couple different materials in a Diaphragm Pump: one used to make the ball and seat, and one to make the body of the pump.

For example, you may see ball and seats made of stainless steel or PTFE for the diaphragm.

The material you should choose depends on your needs. Stainless steel costs more but resists wear for longer. PTFE materials cost less but don't stand up as well to abrasion. Stainless steel is also a good choice if you need a heat-resistant pump. Similarly, a high grade of Stainless Steel is required for Sanitary Diaphragm Pump applications. 

Performance Curve

All of our pumps come with a performance curve which can give you a lot of helpful information.

For example, the performance curve of an air-driven pump will tell you the volume of air that the pump needs at multiple levels of operation. It will also show you how much material can be moved at each operating level and how far it can be taken.

You'll need to pay particular attention to the amount of air that you'll need to provide for the pump, to move as much material as you need it to.

Keep in mind that you'll be aiming to operate the pump at about 50% capacity most of the time. The curve will show you higher operating rates, but you don't want to always operate your pump at the highest rate.

Buying an Air Pump whilst sticking to a budget.

We all know that sticking to the budget set from above can prove tricky sometimes so don't waste money buying the wrong pumps, only to have to replace them later on. A little bit of knowledge goes a long way toward choosing the best Diaphragm Pump for the job. That's why Tapflo should be your number one choice for AOD Pumps, we're the experts and we want to help. 

Ready to Buy a Diaphragm Pump?

With these factors in mind, you'll easily be able to select the right pumps for any application.

Diaphragm Pumps are a great way to get the job done without contributing to pollution and when you choose the best pumps for the job, you won't need to worry as much about maintenance or replacements.

So if you're ready to buy a new pump, Contact us today!

E: [email protected] 

T: 023 8025 2325



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